Motorola MVME166IG/D2 - Manual (Page 82)

Using the 166Bug Debugger
4-12 MVME166 Single Board Computer Installation Guide
4
Example: Trace one instruction using debugger.
166Bug> RD
PC =00010000 SR =2700=TR:OFF_S._7_..... VBR =00000000
USP =0000DFFC MSP =0000EFFC ISP* =0000FFFC SFC =0=F0
DFC =0=F0 CACR =0=........
D0 =00000000 D1 =00000000 D2 =00000000 D3 =00000000
D4 =00000000 D5 =00000000 D6 =00000000 D7 =00000000
A0 =00000000 A1 =00000000 A2 =00000000 A3 =00000000
A4 =00000000 A5 =00000000 A6 =00000000 A7 =0000FFFC
00010000 203C0000 0001 MOVE.L #$1,D0
166Bug> T
PC =00010006 SR =2700=TR:OFF_S._7_..... VBR =00000000
USP =0000DFFC MSP =0000EFFC ISP* =0000FFFC SFC =0=F0
DFC =0=F0 CACR =0=........
D0 =00000001 D1 =00000000 D2 =00000000 D3 =00000000
D4 =00000000 D5 =00000000 D6 =00000000 D7 =00000000
A0 =00000000 A1 =00000000 A2 =00000000 A3 =00000000
A4 =00000000 A5 =00000000 A6 =00000000 A7 =0000FFFC
00010006 D280 ADD.L D0,D1
166Bug>
Notice that the value of the target stack pointer register (A7) has not changed
even though a trace exception has taken place. Your program may either use
the exception vector table provided by 166Bug or it may create a separate
exception vector table of its own. The two following sections detail these two
methods.
Using 166Bug Target Vector Table
The 166Bug initializes and maintains a vector table area for target programs.
A target program is any program started by the bug, either manually with GO
or TR type commands or automatically with the BO command. The start
address of this target vector table area is the base address of the debugger
memory. This address is loaded into the target-state VBR at power up and
cold-start reset and can be observed by using the RD command to display the
target-state registers immediately after power up.